1. Field of the Invention
The invention relates to a tool handle, more particularly to a tool handle that is adapted to be connected to a tool head and that has a handle unit whose orientation relative to the tool head is adjustable.
2. Description of the Related Art
Referring to FIG. 7, a conventional tool handle 10 is shown to include a first handle 11, a second handle 12, an operating member 13 connected movably to the second handle 12, and a lock member 14 mounted in the second handle 12 and connected co-movably to the operating member 13.
The first handle 11 has an inclined first surface 111, an engaging protrusion 112 protruding from the first surface 111, and a pair of diametrically spaced-apart locking grooves 113 formed in the first surface 111 and disposed at opposite sides of the engaging protrusion 112. The second handle 12 has an inclined second surface 121 confronting the first surface 111, and an engaging hole 122 formed in the second surface 121 and engaged rotatably with the engaging protrusion 112.
When the operating member 13 is operated to move the lock member 14 to engage one of the locking grooves 113, the first and second handles 11, 12 are non-rotatable relative to each other. When the operating member 13 is operated to move the lock member 14 to be disengaged from the one of the locking grooves 113, the second handle 12 is rotatable about the engaging protrusion 112 of the first handle 11 to register the other one of the locking grooves 113 with the lock member 14. Then, the lock member 14 is further operable to engage the other one of the lock groove 113 to restrain further rotation of the second handle 12 relative to the first handle 11. As a result, an orientation of the second handle 12 relative to the first handle 11 is adjusted.
In use, when the second handle 12 is mounted with a tool head and the conventional tool handle 10 is rotated to drive rotation of the tool head to, for example, unfasten a screw, the lock member 14 is subjected to a shear force due to a torque transferred from the first handle 11 to the second handle 12. However, since the lock member 14 has a relatively weak structure, it may easily fracture once the torque is too large. Additionally, since the conventional tool handle 10 has only two locking grooves 113, the flexibility of the orientation adjustment of the second handle unit 12 is limited.